Mixers or blenders are used by a variety of industries in order to obtain a substantially uniform admixture that can be processed or fabricated into a final product. If the admixture is not uniform, the final product typically will exhibit or on testing show imperfections or disparities in composition, appearance, or properties. Hence, the mixing operation, sometimes regarded as premixing because mixing precedes the fabrication step, is critical to obtaining a substantially uniform product. Good and effective mixing is particularly difficult in admixing solid particulate, especially solid particulate of varying or different composition, grade, or type. Thus, in the plastics industry, the solid pellets or beads are fed by conventional means as from a hopper to the extruder screw, typically along with one or more additives, which heats and admixes the material as it screw fed to the extruder head. The plastic feed material frequently gets overheated, and/or there is poor admixing of the materials, thereby resulting in an inferior product exhibiting striations, mottling, and the like. For these reasons, mixers, or premixers, for use upstream of the extruder screw, whether for a continuous or batch process, are not customarily in use by the plastic industry.
This invention has therefore as its purpose to provide a mixer for admixing solid particulate, especially plastic particulate of different grades, composition, and type, and with or without other additives, which overcomes the disadvantages of the prior art.